(CNN) -- Jobless Americans topped 15 million this year, according to the Labor Department. About 9 million others work part-time because their hours have been cut or they can't find full-time work. Many of these so-called underemployed workers will be casting ballots November 2.

Americans point to the troubled economy as their most important issue this year when deciding how to vote for Congress, according to a nationwide CNN/Opinion Research Corp. poll. With 42 percent, the economy by far topped other key issues such as health care (with 17 percent), the deficit (13 percent) and education (9 percent.)

Washington first attacked the crisis in fall 2008, after a banking and real estate mess rocked Wall Street and sent housing values plummeting. Then unemployment numbers began soaring.

Wall Street financial firms were in such danger that the Democratic-controlled Congress and the Bush administration approved $700 billion to buy troubled mortgages and other assets to keep them afloat. Supporters said the businesses were "too big to fail": that if the companies were to fail, it would have a devastating effect across the economy.

In December, President Bush approved the use of the same fund for loans that would save U.S. automakers General Motors and Chrysler, which were drowning in debt. GOP lawmakers failed to persuade Bush instead to allow the automakers to seek Chapter 11 bankruptcy protection.

Voter anger

Many voters became angry later, when some of the bailed-out firms continued to hold events at pricey resorts or to use fancy corporate jets to ferry their executives, even to a congressional hearing on the bailout.

Later, Chrysler said it would not be repaying its $7.2 billion government loan because it was filing for bankruptcy. General Motors repaid its $4.7 billion U.S. loan by April 2010.

Issues discussed included ways to prevent companies from growing "too big to fail" -- and hammering out a process to shore up collapsing Wall Street banks.

In 2009, with a new administration in the White House, one of the first actions Congress took as unemployment increased was to pass a $787 billion economic stimulus bill with virtually zero GOP support. Republicans balked at the bill's price tag, saying it was full of unnecessary spending.

The rise of the Tea Party movement was partially fueled by anger over the stimulus bill, said Phillip Dennis, founder of the Dallas, Texas, group. The bill was "the crowning moment of decades of irresponsible government fiscal behavior," Dennis said.

Democrat Rep. David Obey, widely regarded as the author of the stimulus bill and the powerful chairman of the House Appropriations Committee, has chosen to retire in November. He probably would have faced a tough race against a GOP challenger in his Wisconsin home district.

Mounting costs from the bailout bills, the stimulus legislation and the $940 billion health care reform law have prompted voter concern about ballooning budget deficits.

The deficit is the amount of money the government spends over the amount of income it receives. In 2009, the deficit was about nine times the size of those of 2002 and 2007, when Republicans controlled the White House and at least one chamber of Congress, according to the nonpartisan Congressional Budget Office.

This year, the Obama administration is forecasting that the deficit will hit $1.56 trillion.

A higher deficit costs Washington more money because it has to take out more loans to pay for the shortfalls. Paying interest on those loans will mean less available money to pay for goods, services and entitlement programs such as Social Security and Medicare.

A higher deficit also might increase the overall demand for loans because the government is borrowing a lot more of the total loan money that's available. This could make it harder for everybody else to get loans. Under certain conditions, this may result in higher loan interest rates.